Abstract：
BACKGROUND: Approximately 5% of primary total knee arthroplasty patients require revision within 10 years, often due to distal component loosening. Application of a thin layer of PMMA cement as precoating on the tibial component aims to prevent aseptic loosening. This study investigates the impact of precoating and fat contamination on tibial baseplate stability.
METHODS: Two groups of NexGen® stemmed tibial implants (size 4) were studied: Option implants (N = 12) and PMMA Precoat implants (N = 12). Each implant design was divided into two subgroups, (N = 6), with one subgroup featuring bone marrow fat at the implant-cement interface and the other without contamination. In a mechanical testing machine, the implants underwent uniaxial loading for 20,000 cycles, while recording vertical micromotion and migration of the tibial baseplates. Subsequently, a push-out test assessed fixation strength at the cement interfaces. Results were compared using non-parametric statistics and presented as median and min-to-max ranges.
RESULTS: Option implants exhibited higher micromotion in dry conditions compared to precoated implants (p = 0.03). Under contamination, both designs demonstrated similar micromotion values. Fixation strength did not significantly differ between designs under dry, uncontaminated conditions (p > 0.99). However, under contaminated conditions, the failure load for the non-coated Option implant was nearly half that of the uncontaminated counterparts (3517 N, 2603-4367 N vs 7531 N, 5163-9000 N; p = 0.002). Precoat implants displayed less susceptibility to fat contamination (p = 0.30).
CONCLUSIONS: NexGen® implant PMMA precoating might reduce the risk of aseptic loosening and revision surgery in case of eventual bone-marrow fat contamination.
METHODS: Two groups of NexGen® stemmed tibial implants (size 4) were studied: Option implants (N = 12) and PMMA Precoat implants (N = 12). Each implant design was divided into two subgroups, (N = 6), with one subgroup featuring bone marrow fat at the implant-cement interface and the other without contamination. In a mechanical testing machine, the implants underwent uniaxial loading for 20,000 cycles, while recording vertical micromotion and migration of the tibial baseplates. Subsequently, a push-out test assessed fixation strength at the cement interfaces. Results were compared using non-parametric statistics and presented as median and min-to-max ranges.
RESULTS: Option implants exhibited higher micromotion in dry conditions compared to precoated implants (p = 0.03). Under contamination, both designs demonstrated similar micromotion values. Fixation strength did not significantly differ between designs under dry, uncontaminated conditions (p > 0.99). However, under contaminated conditions, the failure load for the non-coated Option implant was nearly half that of the uncontaminated counterparts (3517 N, 2603-4367 N vs 7531 N, 5163-9000 N; p = 0.002). Precoat implants displayed less susceptibility to fat contamination (p = 0.30).
CONCLUSIONS: NexGen® implant PMMA precoating might reduce the risk of aseptic loosening and revision surgery in case of eventual bone-marrow fat contamination.
摘要：
背景：大约5％的初次全膝关节置换术患者需要在10年内进行翻修，往往是由于远端部件松动。在胫骨组件上施加一薄层PMMA水泥作为预涂层旨在防止无菌性松动。这项研究调查了预涂层和脂肪污染对胫骨基板稳定性的影响。
方法：研究了两组NexGen®柄胫骨植入物（尺寸为4）：Option植入物（N=12）和PMMAPrecoat植入物（N=12）。每个植入物设计分为两个亚组，（N=6），一个亚组在植入物-水泥界面处具有骨髓脂肪，另一个没有污染。在机械试验机中，植入物进行了20,000个周期的单轴加载，同时记录胫骨基板的垂直微动和迁移。随后，推出测试评估水泥界面的固定强度。使用非参数统计比较结果,并表示为中值和最小至最大范围。
结果：与预涂植入物相比，Option植入物在干燥条件下表现出更高的微运动（p=0.03）。在污染之下,两种设计都展示了相似的微动值。在干燥条件下,各设计之间的固定强度没有显著差异,无污染条件（p>0.99）。然而,在受污染的条件下，未涂覆的Option植入物的破坏载荷几乎是未被污染的植入物的一半(3517N,2603-4367Nvs7531N，5163-9000牛顿；p=0.002）。预涂层植入物对脂肪污染的敏感性较低（p=0.30）。
结论：NexGen®种植体PMMA预涂层可降低最终骨髓脂肪污染时无菌性松动和翻修手术的风险。
方法：研究了两组NexGen®柄胫骨植入物（尺寸为4）：Option植入物（N=12）和PMMAPrecoat植入物（N=12）。每个植入物设计分为两个亚组，（N=6），一个亚组在植入物-水泥界面处具有骨髓脂肪，另一个没有污染。在机械试验机中，植入物进行了20,000个周期的单轴加载，同时记录胫骨基板的垂直微动和迁移。随后，推出测试评估水泥界面的固定强度。使用非参数统计比较结果,并表示为中值和最小至最大范围。
结果：与预涂植入物相比，Option植入物在干燥条件下表现出更高的微运动（p=0.03）。在污染之下,两种设计都展示了相似的微动值。在干燥条件下,各设计之间的固定强度没有显著差异,无污染条件（p>0.99）。然而,在受污染的条件下，未涂覆的Option植入物的破坏载荷几乎是未被污染的植入物的一半(3517N,2603-4367Nvs7531N，5163-9000牛顿；p=0.002）。预涂层植入物对脂肪污染的敏感性较低（p=0.30）。
结论：NexGen®种植体PMMA预涂层可降低最终骨髓脂肪污染时无菌性松动和翻修手术的风险。
